1. Field of the Invention
The present invention relates to a hybrid compressor system for a refrigeration cycle system of a vehicle, particularly a vehicle having an idling-stop system or a hybrid vehicle.
2. Description of Related Art
Due to the virtue of low fuel consumption, vehicles having an idling-stop system and hybrid vehicles are advantageously marketed lately. Such a vehicle stops its engine according to a driving state (such as temporarily stopped state or a low speed driving state) of the vehicle. Thus, a compressor device of a refrigeration cycle system, which is driven by drive force of such an engine, is also stopped when the engine is stopped, resulting in the non-functional refrigeration cycle system.
To address such a disadvantage, for example, Japanese Unexamined Patent Publication No. 2000-130323 discloses one hybrid compressor system. In this hybrid compressor system, a pulley, which is rotated by drive force of an engine, is connected to one end of a rotatable shaft of a compressor device through an electromagnetic clutch, and a motor is connected to the other end of the rotatable shaft of the compressor device. When the engine is stopped, the electromagnetic clutch is disconnected, and thus the compressor device is driven by the motor. This allows achievement of cooling performance of the refrigeration cycle system irrespective of the operational state of the engine.
However, in the hybrid compressor system disclosed in Japanese Unexamined Patent Publication No. 2000-130323, the motor is used as an auxiliary drive source for driving the compressor device at the time of engine stop, and this publication does not disclose an idea of using a combination of the engine and the motor for driving the compressor device.
In a case where the engine is driven in an idling mode in a temporarily stopped state of a vehicle due to, for example, an operational state of any other auxiliary device or a thermal load state of the refrigeration cycle system, the compressor device is driven by the engine. This causes an increase in the load of the engine, and thus the fuel consumption in the temporarily stopped state of the vehicle cannot be improved.
This is also true in a case of an ordinary vehicle at the time of driving the engine in the idling mode. That is, an idling speed of the engine is increased due to, for example, an operational state of an auxiliary device or a thermal load state of the refrigeration cycle system, resulting in an increase in the fuel consumption.